1. Field of the Invention
The present invention relates to a protection device for electrical appliances, in particular a portable ground fault circuit breaker which interrupts the power of the load side automatically when there is a short circuit, an electricity leakage, an electricity shock, a ground fault, and a neutral ground fault. The breaker also possesses protection functions, such as a water-proof protection.
2. Description of the Related Art
In recent years, fire disasters caused by the short-circuited electrical appliances results in a great loss of human's lives and properties. A further development attendant on the science technique is that people start to design protection devices for these electrical appliances. However, these devices have a poor protection performance generally and provide a narrow application scope. Especially, most protection devices in the market do not have a short-circuited protection function or do not arrange a rational structure even if they have the short-circuited protection function. For example, the devices may lack a function of arc extinction, which creates electric sparks at time of closing, breaks the circuit and the load immediately, and reduces the use duration and comprehensive performances.
There is disclosed a prior art published by a China patent no. ZL 200810147046.0 and titled by “fire-proof and electricity-leakage proof protecting plug” with a short-circuited protection function. As referring to FIG. 1 which is a schematic view showing a tripping structure of the disclosure and FIG. 2 which is a circuit diagram of the disclosure, the prior art includes a tripping solenoid and a multifunctional protection auxiliary circuit installed on a base plate on which a moving iron core sleeved by tripping coils and a framework are all installed, an insulation plate fixedly disposed at a center of a moving contact sheet, a permanent magnet fixedly installed on a place where a pole of the insulation plate and a static iron core on a plug housing are attracted. When a load end of the plug has an overload, an overpressure, an electricity leakage, a short circuit, and/or the plug is overheated, a protection circuit controls the moving iron core for creating magnetism, and the magnetism and the magnetism of the permanent magnet are repulsive. This repulsion drives the permanent magnet to activate a downward motion of the insulation plate and the moving contact sheet, thereby causing a disjunction between the moving and the static contact points and fulfilling a tripping operation.
The above technique has a high sensibility and a quick power-off speed (e.g. power-off within 25 ms). However, the prior art only utilizes the tripping solenoid to fulfill the opening operation. The shortcoming attendant on the mechanism is that it needs enough certain maintenance force to keep the opening/closing state. In other words, when the permanent magnet drives the moving contact sheet to leave the static contact sheet, the moving iron core must reserve a generation of the strong magnetism repulsing the permanent incessantly for assuring the opening safety. However, once the opening operation is obtained, the strong current in the circuit would disappear and subsequently the moving iron core would lose the magnetism incessantly. Due to an elastic and transmutable U-shaped component disposed at one end where the moving contact sheet and the base plate are fixed, the permanent magnet on the insulation plate disposed on the component may be possibly attracted by the static iron core again without the force of incessant repulsion, and such attraction possibly would drive the moving and the static contact sheets to contact with each other again and cause the closing operation, which results in an extreme hidden trouble to the safety.
As referring to FIG. 2 of the disclosure, it is understood that the tripping solenoid is executed by a silicon controlled rectifier to attain the protection against the short circuit, overload, overpressure, electricity leakage or overheat, which however imposes on the silicon controlled rectifier heavily, affects the duration, and increases the hidden trouble to the safety, especially when the short circuit happens.
A further shortcoming is that when the moving contact sheet, the static contact sheet, and the tripping solenoid and the multifunctional protection auxiliary circuit installed on a base plate are all disposed in a smaller space, an electric arcs created by closing the moving and the static contact sheets would inevitably affect or even burn up the tripping solenoid and the multifunctional protection auxiliary circuit.
To solve the shortcomings attendant on the current technique, the inventor of the present invention develops a portable ground fault circuit breaker by combing his abundant technical experiences, the structure of which fulfills a decisive circuit-break effect by opening swiftly and safely, needs not an incessant current supply, and prevents the loss of electrical energy. The present invention also has a compact and scientific structure and possesses a water-proof protection and the function of protecting against the overload, the electricity leakage, the electricity shock, the ground fault and the neutral ground fault, and the short circuit.